Differential herbicidal acid anhydrides of imidic acids and lower alkanoic acids

ABSTRACT

1-Acyloxy 1-(halophenyl)-imino) alkanes, such as 1-propionyloxy 1-((3&#39;&#39;,4&#39;&#39;-dichlorophenyl)-imino) propane, exhibit a strong differential herbicidal effect. While these compounds exhibit an extremely low to zero phytotoxic action when applied to the rice plant, at the same application rate these compounds result in a complete kill of a wide variety of other species of plants commonly found in rice fields as weeds.

United States Patent Galat [54] DIFFERENTIAL HERBICIDAL ACID ANHYDRIDESOFIMIDIC ACIDS AND LOWER ALKANOIC ACIDS [72] Inveiitor: Alexander Galat,1980 South Ocean Drive, Hallandale, Fla. 33009 [22] Filed: March 1, 1971[21] Appl. No.2 119,848

[52] US. Cl ..260/545 R, 71/76, 71/115,

260/562 {51] Int. Cl ..C07c 119/00 [58] Field of Search ..260/490, 545 R[56] References Cited UNITED STATES PATENTS 10/1951 Ritter ..260/545 R[451 Sept. 26, 1972 3,625,990 12/1971 Noguchi et al ..260/545 R PrimaryExaminer-Vivian Garner AtlorneyRobert F. Ruthruff [5 7] ABSTRACT 5Claims, No Drawings DIFFERENTIAL HERBICIDAL ACID ANHYDRIDES OF IMIDICACIDS AND LOWER ALKANOIC ACIDS in inexpensive and readily availablearomatic hydrocarbon solvents.

In certain specific aspects thereof this invention embraces imino estershaving the generic structural formula:

Where R, and R are lower alkyl radicals and X is zero or a whole numberin the range 1 to 5.

Compounds coming within the purview of this invention include l-acyloxyl-((chlorophenyl)-imino) alkanes such as the following:

l-Propionyloxy l-( 3 ',4'-dichlorophenyl )-imino) propane. (Here R, andR are ethyl radicals and X is 2).

, Simply as a matter of convenience this compound is frequentlydesignated PP herein (propionyl propane).

l-Acetyloxy l-(( 3 '4-dichlorophenyl )-imino) propane. (Here R, is themethyl radical and R is the ethyl radical). As a matter, of conveniencethis compound is, on occasion, designated AP herein (acetyl propane).

l-Acetyloxy l-( 3 ,4'-dichlorophenyl )-imino) ethane. (Here both R, andR are methyl radicals and X is 2 as in theprevious compounds.) Asamatter of convenience is now. and then designated AE herein (acetylethane).

l-Propionyloxy l( 3 ,4'-dichlorophenyl )-imino) ethane. (In thiscompound R, is the ethyl radical, R is the methyl radical and, as usual,X is 2.) As a matter of convenience, this compound, on occasion, isdesignated PE herein (propionyl ethane).

As will. appear subsequently, l-propionyloxy 1-( 3 ,4-dichlorophenyl)-imino) propane ap ears to be the preferred compound ofthe four compounds above named. This compound combines the highestphytotoxic effect on a'wide variety of plants (many of which are presentas weeds in rice fields) with an absence of phytotoxicity against-therice plant. Accordingly, the present invention will be described largelyin connection with the preparation, chemical and physical properties anddifferential herbicidal action of this preferred compound.

In general, the compounds of this invention are prepared by reactingarylamines or anilides with acylating agents such as acid anhydrides,acid chlorides, ketenes and the like. The following example sets forth atypical synthesis of l-propionyloxy l-((3'4'- dichlorophenyl)-imino)propane (PP), the preferred compound of this invention.

EXAMPLE 1 Onehundred and sixty two grams (1 mole) of 3,4-dichloroanilinc and 1.62 g. (2.2 moles) of propionic acid were kept atthe boiling point, the water of reaction being allowed to escape bydistillation in the form of the water-propionic acid azeotrope. When thetheoretical amount of water had been removed, remaining excess propionicacid was removed by distillation and the residue was treated with 450 g.propionic anhydride. The resulting mixture was brought to 160 C. andmaintained at this temperature for 10 hours following which the desiredimino ester was separated from the crude reaction mixture by vacuumdistillation. B.P., l60-l 65 C. at about 5 mm. mercury pressure.

Analysis: Calculated for C,,H,;,Cl,NO-,:

C, 52.7% H, 4.74%; C, 53.1% H, 4.54%;

CI, 25.90% N, 5.] l% Cl, 25.70%; N, 5.27%.

Found:

l-Propionyloxy l-((3,4'-dichlorophenyl)-imino) propane is a white,crystalline substance melting at 50-53 C.

While insoluble in water, the compound exhibits an extremely highsolubility in inexpensive, common, organic solvents such as xylene,readily dissolving in half its own weight of xylene.

In the presence of mild alkali PP is hydrolyzed to form 3,4-dichloropropionanilide while in strong alkali hydrolysis to3,4-dichloroaniline occurs.

As will beapparent to those skilled in the chemical art, by suitableselection of reactants any of the other imino A esters set forthpreviously herein may be obtained by following the general preparativeprocedure set forth in the example.

In the initial step of the two step preparative reaction described inthe example, aniline or the aniline derivative reacts with the organicacid to form an equilibrium mixture of the two tautomeric compounds:

H R--CN-- R-C=N- Keto form Imino form In the second step of the two stepreaction, the above tautomeric mixture is treated with an acidanhydride, the acid anhydride reacting with the free hydroxyl group ofthe imino form of the tautomeric pair to produce an imino ester of thisinvention. As is well known to those skilled in the chemical art, thisremoval of the imino form of the tautomeric pair through ester formationupsets the equilibrium between the two tautomers so an additionalquantity of the keto form changes to the imino form in order toreestablish the equilibrium and this new supply of imino form tautomerreacts with the acid anhydride as already described.

As will be evident, in the two step reaction of this syntheticprocedure, if either acetic acid or propionic acid is used in the firststep and either acetic anhydride or propionic anhydride is employed inthe second reaction step, this furnishes four different pairs ofreactants and results in the four different l-acyloxy 1-((3,4-dichlorophenyl)-imino) alkanes specifically named previously herein. Itmay be mentioned as a matter of interest that l-acetyloxy l-((3',4'-dichlorophenyl)- imino) propane (AP) melts at -75 C. (unsharp);lacetyloxy l 3 ',4-dichlorophenyl )-imino) ethane melts at -85 C.(unsharp).

EXAMPLE 2 This example describes a modified synthetic procedure which ismore reproducible, more practical and gives somewhat higher yields thanthat described in Example 1. In this modified procedure, 100 g. 3,4-dichloropropionanilide are dissolved in 375 ml. toluene and the solutionwas treated with 10.5 g. finely divided sodium at 100 C, while stirringunder reflux. After all the sodium had reacted, the temperature of thereaction mixture was reduced to -5 C. and 42.5 g. propionyl chloridedissolved in 125 ml. toluene were added gradually with continuousstirring. The temperature was then raised to 80 C. and the sodiumchloride precipitate was removed by filtration and washed with hottoluene. The combined filtrate and washings were evaporated to drynessunder vacuum, heating under vacuum being continued until constant weightwas obtained. The resulting PP weighed 100 g.

As will be evident to those skilled in the art, by obvious modificationsof certain of the reactants employed in the above synthetic process anyone of the four different l-acyloxyl-((3',4'-dichlorophenyl)-imino)alkanes specifically named previouslyherein may be produced. Thus, in example 2, acetyl chloride may replacethe propionyl chloride of the example to give 1- propionyloxyl-((3',4-dichlorophenyl)-imino)ethane. Similarly, by substituting3,4-dichloroacetanilide for the 3,4-dichloropropionanilide of Example 2,and by using, respectively, propionyl chloride and acetyl chloride toreact with the sodium salt of the imino form of the tautomeric pair,produces, respectively,

acetyloxy l-( 3 ,4'-dichlorophenyl )-imino)propane and l-acetyloxyl-((3',4'-dichlorophenyl)-imino) ethane.

Within experimental limits the l-propionyloxy l-((3',,4'-dichlorophenyl)imino) propane of Example 2 exhibits the samephysical and analytical properties as that obtained via Example I.

I Data on the herbicidal action of several of the compounds of thisinvention on a wide variety of plant species are presented in thefollowing table.

The plants employed in the tests to be described were rice, oats,cucumbers, tomatoes, barnyard grass (Echenochloa crusgalli), pigweed(Chenopodium album) and setaria. The test plants were raised inindividual pots. A staggard date of planting was employed with theseveral test species so that all plants would be at approximately thesame stage of growth at the time of application of the compounds of thisinvention. (Most of the species used here germinate, emerge and grow atapproximately the same rate but tomato plants particularly arerelatively slow starters and accordingly tomato seeds had to be plantedconsiderably earlier than seeds of the other species.)

The pots containing the test plants were placed on a moving belt andspray was applied to them from a stationary nozzle positioned above themoving belt. A spray pressure of 40 pounds per square inch was employedand the rate of application of spray was equivalent to 40 gallons peracre.

Emulsifiable, concentrated hydrocarbon solvent solutions of several ofthe differential herbicides of the present invention were emulsified inwater to produce three dilute test solutions which, when applied at theabove mentioned constant application rate of 40 gallons per acre,resulted in the application of the equivalent of 4, 2 and 1 pounds peracre respectively of the particular differential herbicide under test.

Simultaneous, complementary tests were conducted as above describedemploying 3, 4-dichloropropionanilide as the differential herbicide.This material .was obtained as a commercial emulsifiable solutioncontaining 35 percent by weight of the herbicide and 65 percent solventplus emulsifying agent. It was emulsified in water to form threesolutions of the concentrations set forth in the previous paragraph,that is, 0.1, 0.05 and 0.025 pounds herbicide per gallon so when sprayedat an application rate of 40 gallons per acre the herbicide is appliedat rates of 4, 2 and 1 pounds per acre respectively.

Three replicated pots of each plant species were used for eachindividual differential herbicide tested and for each dosage rateemployed.

After spraying, the plants were observed over a considerable period oftime and the results of the application of spray were evaluated on anarbitrary scale according to which 0 indicates the plants were notaffected while increasing integers indicate an increasing degree ofplant injury to a maximum of 10 which indicates the plants were killedby the particular treatment they received.

The results of these spray tests are summarized in the following table:

TABLE Post Emergence Differential Herbicidal Evaluation differentialrate pig barn setrice oats cucumtomalbs./ weed yard herbicide AC. grassaria her to PP 4 l0 l0 l0 l-TB 9 l0 7 2 l0 9 9 O 5 9 4 I I0 9 8 0 2 8 0PP (Repeat) 4 l0 l0 l0 0 l0 l0 9 2 9 9 l0 0 6 l0 5 l 7 5 7 0 3 7 0 AE 4l0 7 4 0 5 2-l l-Y 2 8 4 2 0 2 O O l 4 l 0 0 l 0 0 AP 4 l0 l0 l0 3 6 l05 2 l0 l0 9 0 3 9 3 l 10 9 7 0 0 6 0 3.4-Dichl0ro 4 l0 l0 l0 2-l 9 l0 l0propion- 2 l0 l0 l0 ll 6 l0 5 anilide 1 l0 3 3 O 2 l0 1 None 0 0 0 0 0 00 PP, AE, AP. For identity of compounds designated thus, see text. TBtip burn l= growth inhibited Y yellowing 1n the Table the first twovertical columns set forth, respectively, the identity of thedifferential herbicide under test and the rate of application thereof inpounds per acre. The remaining seven vertical colums are headed by thesame name of the plant species being tested followed by an evaluation ofthe effect (expressed in accordance with the arbitrary evaluation scalepreviously described in detail herein) of application of the severaldifferential herbicides on the named plant species at each of the threerates of application used.

As will be seen from the data presented there is a gross similarity inactivity of all the differential herbicides tested. The rice plantexhibited a remarkably high degree of tolerance with respect to all ofthe chemicals applied while, in general, all these differentialherbicides exhibited a high degree of activity against all other plantspecies under test. However, compound AE not only is without action onrice plants but also does not have any great effect on cucumber andtomato plants. Incidentally, the tolerance of the tomato plant(generally considered to be a very sensitive plant with respect toherbicides) in the experiments presented here, especially at lowapplication rates, is quite remarkable.

On the basis of the data presented it appears that of the differentialherbicides of the present invention under test, compound PP combinesgreatest safety to the rice plant with the highest activity against theother plant species tested.

It will be noted that 3,4-dichloropropionanilide is generally quitesimilar in action to PP in that rice is relatively tolerant theretowhile this anilide shows a good kill with respect to the other plantspecies tested, especially at the high and intermediate rates ofapplication. 3,4-Dichloropropionanilide appears to have a smallinhibitory effect on the growth of the rice plant at the high andintermediate rates of application but a much more extensive testingprogram with this differential herbicide would be necessary before adefinite statement could be made.

However, 3,4-dichloropropionanilide exhibits a quite definitedisadvantage is comparison with the differential herbicides of thisinvention, this disadvantage being the low solubility of the compound ininexpensive, common organic solvents and disadvantages corollarythereto.

As mentioned previously herein, compound PP (as well as the otherdifferential herbicides of this invention) readily dissolves in half itsown weight of xylene, a readily available and inexpensive solvent.

In contrast, the solubility of 3,4-dichloropropionanilide in xylene isonly about 5 percent, a figure much too low for practical use. Thus, thepumping, drumming, container costs, storage costs (both at the point ofmanufacture and in the vicinity of areas of use), transportation,etcetera of such dilute solutions makes the use thereof economicallyprohibitive.

in order to overcome the disadvantages flowing from the low solubilityof 3,4-dichloropropionanilide in inexpensive organic solvents resort hasbeen had to expensive but extremely powerful solvents such as methylisobutyl ketone, isophorone, and the like, these expensive, powerfulsolvents frequently being diluted with more or less of the readilyavailable, inexpensive solvent such as xylene. A commonly used solventmixture for 3,4-dichlorop rioionanilide is isophorone and xylene inequal volumes. However, even with such powerful solvents and solventmixtures it is not practical to prepare a solution of3,4-dichloropropionanilide containing more than three pounds per gallonof this differential herbicide. This low solubility, even in powerfuland expensive solvents is in distinct contrast to the extremely highsolubility of the differential herbicides of this invention ininexpensive and readily available or anic solvents.

e 1t remembered that while this invention has been described inconnection with specific details and specific embodiments thereof, thesedetails and embodiments are illustrative only and are not to beconsidered limitations on the spirit and scope of said invention exceptin so far as these may be incorporated in the appended claims.

Iclaim:

1. Compounds of the formula:

wherein R and R are alkyl radicals selected from the group consisting ofthe methyl radical and ethyl radical.

2. The compound of claim 1 in which R and R are ethyl radicals.

3. The compound of claim 1 in which R is the methyl radical and R is theethyl radical.

4. The compound of claim 1 in which R and R are methyl radicals.

5. The compound of claim 1 in which R, is the ethyl radical and R is themethyl radical.

2. The compound of claim 1 in which R1 and R2 are ethyl radicals.
 3. The compound of claim 1 in which R1 is the methyl radical and R2 is the ethyl radical.
 4. The compound of claim 1 in which R1 and R2 are methyl radicals.
 5. The compound of claim 1 in which R1 is the ethyl radical and R2 is the methyl radical. 